Commit df3ec5da authored by Steven Rostedt (Google)'s avatar Steven Rostedt (Google)
Browse files

function_graph: Add pid tracing back to function graph tracer 

Now that the function_graph has a main callback that handles the function
graph subops tracing, it no longer honors the pid filtering of ftrace. Add
back this logic in the function_graph code to update the gops callback for
the entry function to test if it should trace the current task or not.

Link: https://lore.kernel.org/linux-trace-kernel/20240603190822.991720703@goodmis.org



Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent c132be2c

include/linux/ftrace.h

+2 −0
Original line number Diff line number Diff line
@@ -1040,6 +1040,7 @@ typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *, 
				      struct fgraph_ops *); /* entry */



extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);

bool ftrace_pids_enabled(struct ftrace_ops *ops);



#ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -1048,6 +1049,7 @@ struct fgraph_ops { 
	trace_func_graph_ret_t		retfunc;

	struct ftrace_ops		ops; /* for the hash lists */

	void				*private;

	trace_func_graph_ent_t		saved_func;

	int				idx;

};

kernel/trace/fgraph.c

+40 −0
Original line number Diff line number Diff line
@@ -854,6 +854,41 @@ void ftrace_graph_exit_task(struct task_struct *t) 
	kfree(ret_stack);

}



static int fgraph_pid_func(struct ftrace_graph_ent *trace,

			   struct fgraph_ops *gops)

{

	struct trace_array *tr = gops->ops.private;

	int pid;



	if (tr) {

		pid = this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid);

		if (pid == FTRACE_PID_IGNORE)

			return 0;

		if (pid != FTRACE_PID_TRACE &&

		    pid != current->pid)

			return 0;

	}



	return gops->saved_func(trace, gops);

}



void fgraph_update_pid_func(void)

{

	struct fgraph_ops *gops;

	struct ftrace_ops *op;



	if (!(graph_ops.flags & FTRACE_OPS_FL_INITIALIZED))

		return;



	list_for_each_entry(op, &graph_ops.subop_list, list) {

		if (op->flags & FTRACE_OPS_FL_PID) {

			gops = container_of(op, struct fgraph_ops, ops);

			gops->entryfunc = ftrace_pids_enabled(op) ?

				fgraph_pid_func : gops->saved_func;

		}

	}

}



/* Allocate a return stack for each task */

static int start_graph_tracing(void)

{
@@ -931,11 +966,15 @@ int register_ftrace_graph(struct fgraph_ops *gops) 
		command = FTRACE_START_FUNC_RET;

	}



	/* Always save the function, and reset at unregistering */

	gops->saved_func = gops->entryfunc;



	ret = ftrace_startup_subops(&graph_ops, &gops->ops, command);

error:

	if (ret) {

		fgraph_array[i] = &fgraph_stub;

		ftrace_graph_active--;

		gops->saved_func = NULL;

	}

out:

	mutex_unlock(&ftrace_lock);
@@ -979,5 +1018,6 @@ void unregister_ftrace_graph(struct fgraph_ops *gops) 
		unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);

	}

 out:

	gops->saved_func = NULL;

	mutex_unlock(&ftrace_lock);

}

kernel/trace/ftrace.c

+3 −2
Original line number Diff line number Diff line
@@ -100,7 +100,7 @@ struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end; 
/* What to set function_trace_op to */

static struct ftrace_ops *set_function_trace_op;



static bool ftrace_pids_enabled(struct ftrace_ops *ops)

bool ftrace_pids_enabled(struct ftrace_ops *ops)

{

	struct trace_array *tr;
@@ -402,10 +402,11 @@ static void ftrace_update_pid_func(void) 
		if (op->flags & FTRACE_OPS_FL_PID) {

			op->func = ftrace_pids_enabled(op) ?

				ftrace_pid_func : op->saved_func;

			ftrace_update_trampoline(op);

		}

	} while_for_each_ftrace_op(op);



	fgraph_update_pid_func();



	update_ftrace_function();

}

kernel/trace/ftrace_internal.h

+2 −0
Original line number Diff line number Diff line
@@ -43,8 +43,10 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs) 


#ifdef CONFIG_FUNCTION_GRAPH_TRACER

extern int ftrace_graph_active;

extern void fgraph_update_pid_func(void);

#else /* !CONFIG_FUNCTION_GRAPH_TRACER */

# define ftrace_graph_active 0

static inline void fgraph_update_pid_func(void) {}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



#else /* !CONFIG_FUNCTION_TRACER */